Field of the Invention
The present invention generally pertains to an inkjet print head.
Description of Related Art
Multiple kinds of inkjet print heads are well known in the art. In one kind of inkjet print head, a continuous flow of ink is circulated from an ink reservoir through the inkjet print head and back to the reservoir. Such ink circulation enables removal of debris and/or gas bubbles from the print head. US 2009/0284572 A1 discloses such a print head. Further, it is known to use a lithographically manufactured substrate for forming very small fluidic structures enabling high-frequency operation for expelling very small droplets allowing image forming on a recording substrate with a very high resolution. A disadvantage of such very small structures is found in very small particles being able to enter the fluidic structures and blocking the fluid flow or disrupting the droplet formation in any other way. So, it is preferred to prevent such small particles from entering the lithographically manufactured structure.
US 2009/0284572 A1 discloses that it is not preferable to include a filter in an ink circulation path. In particular, it is disclosed that air bubbles are blocked by the filter preventing the air bubbles from being transported back to the ink reservoir, where they can disappear from the ink. Moreover, in the embodiment illustrated in FIG. 30 of US 2009/0284572 A1, it will be hard, if not impossible, to purge the air bubbles together with the ink through the nozzles. Hence, it is suggested not to apply a filter in an ink circulation path in the print head and, consequently, debris being circulated may eventually enter the lithographically manufactured fluidic structures
It is an object of the present invention to provide an inkjet print head with a continuous flow through the print head, wherein it is prevented that circulating debris may enter fluidic structures of a droplet forming unit.